The present invention relates to a variable valve system and the like for an internal combustion engine, in which an engine valve can be stopped according to an operating state of the internal combustion engine.
Japanese Patent Application Publication No. 2007-100585 discloses a previously-proposed variable valve system for an internal combustion engine. In this technique, a lash adjuster switches between an opening-and-closing operation of an engine valve and a stop of the opening-and-closing operation. The lash adjuster includes a tubular body portion, a plunger portion and a switching mechanism portion. Whole of the tubular body portion is accommodated in a case fixed to a cylinder head, and is upwardly biased by a spring. The tubular body portion is slidable inside the case in an up-down direction. The plunger portion is provided inside the tubular body portion to be slidable in the up-down direction relative to the tubular body portion. An upper end side of the plunger portion supports one end portion of a rocker arm. The switching mechanism portion switches between the operating state and the operation-stopped state of the engine valve which is opened and closed by a swing motion of the rocker arm.
A connecting pin of the switching mechanism portion moves in communication holes of the tubular body portion and the case by means of oil pressure. Accordingly, the tubular body portion (lash adjuster) is locked to an engine main body such that the engine valve is brought into the operating state, or is made to do a lost motion such that the engine value is brought into the operation-stopped state. This switching is performed in order to improve fuel economy and output of the engine.